Did you notice how Michael Phelps lingered on his blocks just a touch at the start of the 4x200m free. No medal in the 400IM, silver in the sprint relay, pipped by young Chad in the 200 'fly, a massive margin of comfort gifted to him by his teammates. It all added up: lets's not get disqualified, let's nail the 19th.

The crowd roared him on in appreciation not simply of another race won or the skills that even now at this less-than-golden swansong are an absolute joy to behold.

He is here despite it all, for the good of others as much as self this time, here to enjoy it too. Not much fun getting beaten, as he acknowledged, but fun to take in the festival around you for the first time since you were 15 before the blinkers had to go on - and for the rest of his life to savour the most soaring career we have ever seen.

Olympic Games: 19 medals (15G, 2S, 2B) 2004-2008-2012

World Championships: 33 medals (26G, 6S, 1B) 2001-2011

Some argue that the showmen and women of the Games are the ones who stand out as greatest of all, even if they may have had but a single moment of glory. I disagree. Phelps has it all: single moments of wuthering wonder combined with multi-skills many will ever only dream of and with longevity.

Phelps may not be winning everything here in London but he is laying down a record for the ages. Many of us will be long gone before anything like this happens again.

We were here when it happened. How lucky are we.

Phelps swam into history with a lot of help from his friends, taking down the last major record that wasn't his alone. He took the anchor leg for the United States in a gold medal-winning performance of the 4x200-meter freestyle relay Tuesday night, earning the 19th Olympic medal of his brilliant career, and the 15th gold.

About an hour earlier, Phelps had lost the one he truly wanted, let his signature slip out of tune. If it was painful to watch, it must have been agony to endure. The race tied him with Latynina but on the podium Phelps could barely smile, his demeanour the same as that when he tossed his cap off in frustration at the end of the last 200m butterfly he will ever swim, mum and other family, as ever, there to cheer, to support, to celebrate the greatest of greats, alias a son and brother.

Before the relay there was a change of mood, the Americans huddling together, history and the hand of responsibility calling them to the water. "I thanked those guys for helping me get to this moment," Phelps said. "I told those guys I wanted a big lead. I was like, 'You better give me a big lead going into the last lap,' and they gave it to me. I just wanted to hold on. I thanked them for being able to allow me to have this moment."

Berens handed Phelps an advantage over Gaul and their chief warrior Yannick Agnel of almost 4sec. Not even heavy legs would stop Phelps this time. He brought it home to the cries and fist-punching of his teammates on deck, the crowd rattling the rafters. "You are now a complete legend!" came the blast from the public-address system.

Phelps arrived in London the most golden Olympian of all time by a big margin. Now he is the undisputed greatest of greats, with 15 golds among 19 medals. Astonishing. The legacy will last and last.

"The legacy he has left behind for swimming is fantastic," said Le Clos, the new champion of 200m butterfly. "Even in Africa, everyone knows Michael Phelps."

Two more chances for the solo triple remain: 100m butterfly and the 200m medley. After the 200m tonight, others must sense the vulnerability of Phelps. Can he find one more strand of strength in him to write another line in a history book that already demands a shelf of its own?

Seems he'll do what he can - try. "It has been a pretty amazing career but we still have a couple races to go," he said before walking away last night, the last wall four days away.

Holst, composer of The Planets, his daughter Imogen once recalled, "hated incomplete performances of The Planets, though on several occasions he had to agree to conduct three or four movements at Queen's Hall concerts. He particularly disliked having to finish with Jupiter, to make a 'happy ending', for, as he himself said, 'in the real work the end is not happy at all'." Perhaps not but it is what is is and probably what it was supposed to be.

Come August 4th and the deed be done, Phelps will dive off this rock into another moment. He leaves behind a simple message, one that he has often repeated: "I just go in to do my best." He gave it his best today and someone was better. It is the best of us when we try the very hardest we can, even though the result can be painful.